Recording-completing cord and trunk circuits



Apnl 28, 1953 R. B. BUCHANAN RECORDING-COMPLETING CORD AND TRUNK CIRCUITS Filed Dec. 29. 1948 4 Sheds-Sheet 1 /A/l/EA/ro@ By R. B. BUCHANAN A T TORNE V April 28, 1953 R. B. BUCHANAN RECORDING-CCMPLETING CORD AND TRUNK CIRCUITS 4 Sheets-Sheet 2 Filed Dec.

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April 28, 1953 R. B. BUCHANAN RECORDING-COMPLETING CORD AND TRUNK CIRCUITS Filed Dec. 29. 1948 4 Sheets-Sheet 5 /NVE/v TOR R. B. BUCHANAN 'A TURA/Ey April 28, 1953 R. B. BUCHANAN RECORDING-COMPLETING CORD AND TRUNK CIRCUITS Filed Dec. 29. 1948 `4 Sheets-Sheet 4 VX RB. BUCHANAN ATTORNEY Patented Apr. 28, 1953 RECORDING-COMPLETING CORD AND TRUNK CIRCUITS Russell B. Buchanan, Lynbrook, N. Y., assigner to BellTelephone Laboratories, Incorporated, New York, N. Y., a. corporation of New York Application December 29, 1948, Serial No. 67,868

4 Claims.

This invention relates to telephone systems and particularly to systems comprising automatic local oices and switchboards including manual switching operator positions.

In areas in which local office subscribers dial to originate all toll calls, the dial systems A operators to which such calls are automatically extended may be able to complete only the short-haul toll calls; and calls to more distant points are completed by toll operators, the calling subscriber being asked to hang up until called back by a toll operator. Objects of the invention are an increased efficiency in the completion of toll calls from local dial office subscriber stations and the provision of switching means which enables the extension of such calls from dial system A operator positions to toll operator positions on a recording-completing basis, that is, without requiring that the calling subscriber hang up and waity until called by a toll operator.

This invention is a recording-completing cord for use at dial systems A operator positions in connecting recording-completing trunks incoming from local dial oflices to other recordingcompleting trunks outgoing to toll operator positions. A feature of the invention is an arrange- -ment whereby the two-way transmission of j supervisory signals between interconnected incoming and outgoing recording-completing trunks is effected over the sleeve conductor of the dial systems A operator cord circuit through which these trunks are connected, ringing and coin-control signals being transmitted through the talking conductors.

The invention and its features are further explained herein by describing a system comprising local and toll oiiices in which the invention is embodied, one such a system being shown schematically in the drawing which consists of Figs. '1 to 5, inclusive.

Referring to the drawing:

Fig. 1 shows a local dial oiiice including an outgoing recording-completing trunk circuit 22, a trunk Tl, and a recording-completing trunk circuit 30, incoming to a dial systems A switchboard located in a toll cnice;

Fig. 2` shows a dial systems ,A operator position comprising cord circuits 40 and 50 and position and telephone circuits 18; j

Fig. 3 shows an operators recording-completing trunk circuit 80 associated with a trunk T2 outgoing from the dial systems A operator position to a toll operator position;

Fig. 4 shows an incoming recording-completing trunk circuit |30, connecting trunk T2 to a toll operator position; and

Fig. 5 shows the relative position in which Figs. 1 to 4 are to be placed to form an operative arrangement.

General description The local dial ol-Iice shown in Fig. 1 may include switches of any known type, for instance step-by-step, panel or crossbar, but it will be assumed that this oiiice is equipped with switches of the step-by-step type. The dial oiiice comprises subscriber station I0 and line L, a line linder LF, a selector S, a coin trunk circuit l2 individually interconnecting line nder LF and selector S, an outgoing recording-completing trunk circuit 22 and a coin control trunk circuit 23. This oice also includes connector switches, none of which are shown, for connecting with called subscriber lines. The subscriber stations are of the common battery type and each station includes a dial or other impulse sender for directly controlling the switches through which desired connections are established. The subscriber station l0 is of the prepayment coin box v type but other stations may be iiat rate or message rate stations. For a description of the structure of step-by-step switches and their operation when used as selectors and connectors, reference may be made to pages 53 to 56, inclusive, of Automatic Telephony by Smith and Campbell, second edition, published in 1920. Reference may be had to the patent to R. L. Stokely, No. 1,799,654, April 7, '1931, for a description of a step-by-step line finder. The line iinder LF and selector S are each represented by a set of brushes and a single set of terminals, the other terminals, associated electromagnets, relays and other apparatus all being omitted. The coin trunk circuit I2, shown in block form in Fig. 1, provides means for detecting the presence of a coin in the coin box of the subscriber station and means for controlling the collecting and refunding of coins deposited at coin subscriber stations. Reference may be had to Patent 2,427,000, granted September 9, 1947, to H. Hovland, for a complete disclosure of such a coin trunk circuit. Non-coin subscriber lines are served by a different group of line nders which connect subscriber lines directly to selectorswitches. The outgoing recording-completing trunk circuit 22 may be similar to the trunk circuit B disclosed in Patent 1,753,334, granted April 8, 1930, to T. V. Curley. Only so much of 3 trunk circuit 22 is shown as is required for a complete description of the invention.

The incoming recording-completing trunk circuit 30 is jack-ended at a dial system A switchboard which is shown in the drawing as being located in a toll oice. This A switchboard may, however, be located in the dial office or may be located in an oriice remote both from the dial oice and the toll office. The dial systems A operator cord, position and telephone circuits are shown in schematic form; and reference may be had to Patent 2,276,515, granted March 17, 1942, to T. D. Robb, for a complete disclosure of such circuits. In addition to the cord circuits 40, which are used to extend short haul toll calls, each A operator position is provided with recording-completing cord circuits 50 for use in extending calls completed over intertoll trunks, one such cord circuit being shown in detail. The cord circuit 40 is used to answer calls incomingtc trunk circuit 30 from the dial ofce; and, if the called line is located in another local cnice in the same local area, the incoming trunk circuit 30 isfdirectl'yconnected by the cord circuit 40 to an outgoing trunk circuit 44, thence over the associated trunk to the called local cnice. If, however, the called line is located in an office requiring the extension of the connection over an intertoll trunk, the A operator connects one plug of a recording-*completing cord circuit 50 to the incoming trunk circuit 30, in place `of the cord circuit 40 which was used to answer the call; and connects the other plug to an loutgoing Aoperator recording-completing trunk circuit S0, thence over the associated trunk T2 to an incoming trunk circuit |30 which is jack-ended at an outward operator position of the toil board. A trunk coin control circuit |20 is individually associated with the trunk circuit B and a similar 'trunk coin control circuit 23 is subscriber at a prepayment 'coin subscriber station I0, an idle line n'der LF is operated'to connect the Ysubscriber line L to the coin trunk circuit |2 andthroug'h this circuit to a rst selector S. Assume that the calling subscriber dials the digit 0, in which case the selector S is operated fto select the group of terminals which are connected to outgoing recording-'completing trunks. The selectors S automatically select a set of terminals which are #connected to an idle trunk 4circuit 22 which is connected lby the conductors lof trunk TI to an incoming recording-completing trunk circuit 30 terminating in a jack 35 at a dial system A operator position. The seizure of trunk circuit 22 causes the lighting vof 'the line lamp 34 of trunk circuit v30; and the call is answered by connecting the plug '4| of an idle cord circuit 40 -to the jack 35. 'The lamp 34 -is thereby extinguished and the calling subscriber informs the operator as to the called subscribers directory number. If the called subscriber line terminates ina local ofce to which the operator has access over direct trunks, the plug 42 is connected to jack 43 of an outgoing trunk circuit 'M associated with a trunk leading to the called .localfoiiice If, however. the call tems operator.

is one completed over an intertoll trunk to which the dial systems A operator does not have direct access, the call is extended through an outgoing recording-completing trunk circuit 80, trunk T2 and incoming trunk circuit |30 which terminates at jack |4| of a toll operator position. The one or the other of two operating methods may be used by the dial systems operator to extend a call over an intertoll trunk. According to one method, the operator disconnects the cord circuit '40 from jack 35, connects plug 5| of a recording-completing cord circuit 50 to jack 35, and connects plug 12 to jack 19 of an outgoing recording-completing trunk circuit 80. The seizure of trunk circuit 80 causes the lighting of a line lamp '|35 at the toll position. When a toll operator answers the call by connecting the plug 0f a cord circuit |50 to jack |4|, line lamp is extinguished and the toll operator may then receive the details of the call from Vthe calling subscriber. The dial systems A"operator 'takes no 'further action on the call until the supervisory lamp 17| 'is lighted responsive 'to a disconnect or recall signal received from the toll operator position. When using 'the other method referred to above, the dial systems A" operator connects the plug 12 of a cord circuit 58 to a jack T9 without rst disconnecting 'cord circuit .fromjack 35. 4A signal is thereby transmitted over trunk T2 to light the Aline lamp |35 at the toll operator position. When Aa toll operator connects plug |5| of a cord circuit |50 to jack |4|, lamp |35 is extinguished and the operator obtains the details of the call 'from the dial sys- Thedial systems A operator thereupon disconnects-cord circuit y40 from jack 35 and connects plug 5| of cord circuit 50 to jack 35 and takes no further action until the supervisory lamp 7l is lighted responsive to a disconnect o'r recall `signal received ffrom the toll operator position.

When a call froma coin subscriber station has been completed, fthe collection or refund of coins deposited -at the 'calling stationis efected by operation vof the toll operators position coin collect or refund key, as required. 'Switchhook supervision is transmitted from fthe calling subscriber station Ito the toll switchboard. When the calling subscriber restores the telephone to normal at the endof conversation, the toll operator Ireceives the disconnect 'signal and disconnects vcord from trunk circuit |30. A disconnect signal is thereby given to the dial systems .Aoperator by the lighting Aof lamp Jl; whereupon cord circuit 50 is disconnected vfrom jacks "35 and 19 and the switches in the dial office are 'restored to normal.

rDetailed description Assume that-the subscriber at station l0 loriginates a call, that a line find-er LF operates 'to connect the line L through coin trunk circuit I2 to selector S, that a-coin is deposited at the calling station, y'that the subscriber dials `the digit() and that the selector S is thereby operated to connect with a vrecoruhig-completing trunk circuit 22. When trunk circuit 122 is seized, the coin control rtrunk circuit f|2 operates to establish a direct connection between -the calling'line and the trunk circuit^22 in the manner described in the 'aforementioned Hovland patent, whereby a circuit is closed `for 'operating relay 8. The operation ofvfrelay' causes'thesuccessive operation of relays I5, I8 and 20; and 'the operation 'of relay 20 closes ia circuit for .operating relay 25 5 of trunk `circuit 30. The circuit for operating relay 25 is traced from ground through theupper winding of relay 2|, front contacts of relays 20 and l5, upper right winding of repeating coil upper conductor of trunk TI, upper left winding of repeating coil 24 of trunk circuit 35, a back contact of relay 29, both windings of polarized relay 25, lower left winding of repeating coil 24, lower conductor of trunk TI, lower right winding of repeating coil I front contacts of relays I5 and 20 and through the lower winding of relay 2| to battery. Relay 2| is marginal and is not operatively energized in this circuit because the current is limited by the high resistance of the lower winding of relay 25. The operation of relay 25 closes a circuit for operating relay 26; and relay 25 closes a circuit for lighting the line lamp 34 associated with answering jack 35. When a dial systems A operator answers the call by inserting plug 4| of a cord circuit 40 in jack 35. a circuit is closed from battery in the operators position circuit, through the sleeve conductors of cord 49 and jack 35, and through the lower winding of relay 21 of trunk circuit 30, to ground. Relay 21 operates, closing a circuit for operating relay 28. The operation of relay 28 extinguishes the line lamp 34, short circuits the lower, high resistance .winding of relay 25, and

vcloses a talking current transmission path through condenser 3| and repeating coil-24. The short circuiting of the high resistance winding of relay 25 increases the current through the windings of realy 2| of outgoing recording-completing trunk circuit 22; and the operation of relay 2| causes the return of the coin initially deposited at the calling station I8 in the manner described in detail in the aforementioned Curley patent.

rThecalling subscriber now informs the answering operator as to the directory number of the called line; and, if the call can be completed directly by this operator, the plug 42 is connected to a jack 43 associated with the trunk circuit 44. If, however, the call is one which must be routed to a toll operator position, and the second of the two aforementioned operating methods is employed, the dial systems A operator connects the plug 12 of a recording-completing cord circuit 50 to the jack 19 of an idle outgoing recording-completing trunk circuit 80. With the talking key 68 of the cord 50 operated and assuming that there are no other talking keys operated at this operator position, a, circuit for operating relay 5| is closed through conductor 62 to ground in the position circuit 18. Relay 5| operates, locks through conductor 55 to ground in the position circuit 18, extends the locking ground through conductor 54 to the position circuit 18, and closes a circuit for operating relay 59. The operation of relay 59 connects ground through its middle upper front contact, resistor 56 and a back contact of relay 54 in series thence through theupper winding of relay 51 to battery and also through the lower winding of relay 51 in series with resistor 58, a back contact of relay 14 and resistor 15 to battery; but relay 51 does not operate at this time because the windings are oppositely energized. The connection of plug 12 to jack 19 closes a circuit from battery through the winding of relay 13, a back contact of relay 1|, the sleeve conductors of plug 12 and jack 19, a back contact of relay 84 of the outgoing recording-completing trunk circuit 88, and winding of relay 89 to ground. Relays 13 and 89 operate. The operation of relay 13 completes a circuit for operating relay 1|; and the operation of relay 89 closes a circuit for operating relay 81. Relay 81 connects interrupter INT through resistor 88 t0 the sleeve conductor; but the interrupter is without useful function at this time. Relay 1| locks under control of relay 59, opens its own operating circuit, opens the busy test connection between the tip of plug 12 and the operators telephone set, and connects the tip and ring of plug 12 through condensers 69 and 10 to the telephone set. Relay 1| disconnects the sleeve conductor of plug 12 from the winding of relay 13 and connects this conductor to a front contact of relay 59, thence through resistor 58 to the lower winding of relay 51 and also through a back contact of relay 14 and resistor 15 to battery; whereby relay 13 releases, and relay 89 is held operated. The aforementioned operation of relays 1| and 81 closes a circuit from battery through the inner lower back contact of relay 14, a front contact of relay 1|, the ring conductors of plug 12 and jack 19, lower left winding of repeating coil 8| of trunk circuit 88, winding of relay 83, a back contact of relay 84, and a front contact of relay 81 to ground. Relay 83 operates, locks independent of relay 84, and closes a circuit for operating relay 84. Relay 84 locks under control of relay 81; opens the operating circuit of relay 83; closes a circuit for operating relay 14 from ground through the left front contact of relay 83, a front contact of relay 84, upper left winding of repeating coil 8|, tip conductors of jack 19 and plug 12, a front contact of relay 1|, and a back contact and winding of relay 14 to battery. Relay 14 operates; locks under control of relay 59; opens its own operating circuit; disconnects battery from the ring conductor of plug 12, thereby causing the release of relay 93; closes connections between the tip and ring conductors of plugs 5| and 12; closes a connection from ground through the uppermost front contact of relay 6|, a front contact of relay 14, and conductor 86 to condition the position circuit 18 for conversation between the telephone set of this circuit and a toll operator; and opens the connection from battery through resistor 15 to windings of relay 51. The aforementioned operation of relay 84 disconnects vthe winding of relay 85 from the sleeve conductor of jack 19 and closes a connection from this conductor through resistor 9| and left winding of relay 92 thence to battery through the right winding of relay 92 in parallel with resistor 94. Relay 92 is thereby operated by the energization ofv its windings in series aiding; but relay 51 does not operate since its lower winding continues to be energized differentially with respect to its upper winding after relay 14 operates, in series with the windings of relay 92. The operation of relay 92 closes a circuit for operating relay 98 and relay 9|) holds relay 81 operated after relay 89 releases. The operation of relay 98 closes a circuit including a front contact of relay 84 and a back contact of relay 98 for operating relay 98. Relay 96 connects ground through resistor 95, in place of battery through resistor 94, to the windings of relay 92 thereby balancing the potentials applied to the sleeve conductors of plug 12 and jack 19 so that there is substantially no current therethrough whereupon relay 51 is operated due to the energization of its upper winding alone and relay 92 remains operated due to the energization of its right winding alone. The operation of relay 51 closes a locking circuit for relay 59. The aforementioned operation of relay also closes a circuitdor operating relay U8. Relay lil closes a circuit for operating relay |69. vRelay |109 Aoperates, locks through conductor :85 under control cuit |38. The circuit -for operating relay |31 is Atraced from battery through the right winding of relay H40, iront contacts of relays |09 .and |618, resistor :|.|.2, conductor cil, lower right winding of repeating coil 8|, conductor |02 of trunk T2, lower left .winding of repeating coil |39 of trunk circuit |30, 'both windings .of relay 13|, upper back contact of relay |31, upper Vleft :winding of repeating coil |39, conductor lui of trunk T2, upper right winding .of repeating coil 8|, conductor |65, resistor |01, iront contacts of relays |08 and |09 and through the left Winding of relay to ground. Relay |3| operates vbut the lower winding of relay `|3| is a high resistance winding and limits the current in this circuit to prevent the operation of relay |10. The operation of relay |53| disconnects ground from .the upper `winding of relay |33 and closes acircuit lfor operating relay |32. The operation of relay |32 closes a circuit for lighting lamp |35 as a calling signal to indicate that there is a call `awaiting answer.

When a toil operator answers the call by connecting the plug of `a cord circuit |55 to answering jack |4|, a circuit is closed through the sleeve conductor of plug |5| and jack |4| for operatively energizing the lower, resistance winding of relay |33. The operation of relay |33 closes a circuit for operating relay |35. The operation ci relay |34 cxtinguishes lamp |35; connects talking condenser in serios with the left windings of repeating coil |39; and closes a short circuit across the lower, high resistance winding of relay |3| thereby to cause the operation of relay H0 .of trunk circuit dil. The operation of relay Il@ closes a circuit for operating relay I The operation of relay bridges relay ||3 in series with condenser ||4 across the conductors of trunk T2; connects ground to conductor 86 to further lock relay 84 operated; and closes a. circuit including conductor 96 for operating relay SS. Relay Q3 operates; locks through conductor 85 under the control of relay `8.4; connects the talking condenser |00 in series with the right windings of repeating coil 8|; opens the operating circuit of relay 96; and closes a holding circuit for relay 96 which is traced through the left front contact of relay 93, conductor 9S, front contact of relay conductor B5 and a front contact of relay 84 to ground. The

talking key (not shown) of cord circuit having been operated, the toll operator obtains the information necessary for completion of the connection to the called subscriber from the dial Systems A operator. After the dial systems A operator has passed the necessary information to the toll operator, the plug 4| of cord circuit 40 is disconnected from jack 35; and the plug 5| of cord circuit 5|! is connected to jack 35 and the talking key is restored to normal. When the talking key 63 of cord circuit 50 is restored to normal, relay 6| releases disconnecting the position and telephone circuits 'I8 from cord 50. The dial systems A operator takes no further action until a recall or a, disconnect signal is received from the toll operator as hereinafter described. When plug 5| is connected to jack 35, relay 2l of trunk circuit 3G is operated and relays 52 and 53 of cord circuit 5c are energized. Relay 53 operates but relay 52 is marginal and does not operate due to the high resistance of the lower v`winding of relay 2l. The operation of relay 53 connects the winding of relay 5.9 Ato ground at the back Contact of relay v54 thereby to hold relay '.59 operated, independent .of relay 57|, after relay 6i releases.

The calling line L is thus connected through trunks TI and 'lf2 and cord circuit 50 to the .toll operators cord circuit |59; and, when the toll operator completes the call, talking currents are transmitted through repeating coils li, 24, 8| and |39 of trunk circuits .22, 3|?, 89 and |36.

The 'toll operators position circuit |55 includes .coin `collect and coin return keys (not shown) for use :in collecting and refunding coins deposited at the calling subscriber station. The operation of the :coin collect key connects coin collect battery tothe ring conductor of plug and the operation of the coin return key connects coin return battery, of opposite polarity, to the ring conductor of plug |5I. In either case, relay `|45 of vtrunk circuit |35 vis operated. The operation of relay closes a circuit for operating relay |46. The operation of relay |45 disconnects the ring conductor of jack |41 from repeating coil |38 and connects this conductor through a trunk conductor |4.'| to the trunk coin control circuit |20 which is individually associated with trunk circuit 80, through `the Windings of oppositely polarized relays |2| and |22, vresistor |26 and the winding of relay |21 to ground. Relay |2| is operated by current from the coin collect battery, relay |22 is operated by current from the coin return battery, and relay |27 is operated by current of either polarity. The operation of relay |21 closes a circuit for Aoperating relay |22 and the operation of the one or the other of relays |2| and |22, closes a circuit from the corresponding one of coin control batteries |23 and |24 through the winding of relay |25, front contact of relay |28, conductor |04, lower left winding of repeating coil 8|, ring conductors of jack 19 and plug l2, front contacts of relays 'H and 14, ring conductors of plug 5| and jack 35, and winding of relay 37 of trunk circuit 30 to ground. Relay 3'| operates, closing a circuit for operating relay 38. The operation of relay 38 disconnects the ring conductor of jack 35 from the lower right winding of repeating coil 24 and connects this conductor to a trunk conductor 39 which extends to the trunk coin control circuit 23 which is individually associated with trunk circuit 22 in the local dial oice. The trunk coin control circuit 23 is thus rendered effective to connect coin control battery of the required polarity to the ring conductor of trunk circuit 22 in the same manner that coin control trunk circuit |20 connects the desired one of batteries |23 and |24 to the ring conductor of jack 19; whereby the coins deposited at the calling station are collected or returned as desired in usual and well-known manner. Assuming that there is a coin in the coin box at the calling station at the time that the coin collect or return key is operated by the toll operator, the marginal relay (not shown) of trunk coin control circuit 23, which corresponds to relay |25 of trunk coin control circuit |20, is operated; whereby the resistance in series with conductor 39 is reduced to cause the operation of marginal relay |25. The operation of relay |25 short circuits resistor |26 to cause the operation of a marginal relay (not shown) in position circuit |55 and the lighting of a coin pilot lamp (not shown) as an indication that coin collect or return battery is being applied to the calling sub- 9 scribersline and that there is a coin in the coin box.- After the coin is collected or returned, further operation of the coin key is ineffective to cause the lighting of the coin pilot lamp.

If the calling subscriber intermittently actuates the receiver hook to signal the operator, each of relays 8 and I5 of trunk circuit 22 alternately releases and reoperates thereby causing reversals of current through trunk TI to release and reoperate relay 25 of trunk circuit 20. Each release and reoperation of relay 25 connects ground to and disconnects ground from the low resistance upper winding of relay 21 whereby the marginal relay 52 of cord circuit 50 is alternately operated and released. Each operation and releose of relay 52 effects the operation and release of relay 54, whereby battery through resistor 55 is intermittently connected to the windings of relay 51 thus causing a corresponding release and reoperation of relay 92 of trunk circuit 80. Each release and reoperation of relay 92 causes the corresponding release and reoperation of relays 90 and 08 in succession. Each release and reoperation of relay |08 reverses the current through trunk T2 whereby polarized relay |3| is alternately released and reoperated; and the connection and disconnection of ground to the upper, low resistance winding of relay |33 causes the ashing of the supervisory lamp |53 of cord |50. When the calling subscriber stops actuating the receiver hook, the lamp remains extinguished. When the calling subscriber replaces the receiver on the receiver hook at the end of conversation, the lamp |53 is lighted steadily as a disconnect signal. The connection between line L and the toll operator is. however, under the control of the operators, relay I8 of trunk circuit 22 being held operated under the joint control of relays 8 and 2 I.

If after the calling subscriber has replaced the receiver on the receiver hook, the toll operator wishes to recall the subscriber, operation of the ringing key (not shown) of cord circuit |50 connects battery to the tip of plug |5| to operate relay |31 of trunk circuit |30, The operation of relay |31 connects ringing s-ource |38 to the conductors of trunk. T2 to operate relay I3 of trunk circuit 80. The operation of relay ||3 closes a circuit from battery through resistor ||5 and front contact of relay ||3, conductor |03, upper left winding of repeating coil 8|, tip conductors of jack 19 and plug 12, front contacts of relays 1| and 14, tip conductors of plug 5| `and jack 35, upper right winding of repeating coil 24 and winding of relay 29 to ground. Relay 29 operates, connecting ringing source 35 to the conductors of trunk TI; whereby trunk circuit 22 is rendered effective to transmit ringing current to the calling line. When the ringing key is released, relays ||3 and 29 release; and when the calling subscriber answers the ring, the supervisory relays of trunk circuits 22 and 30, cord circuit 50, and trunk circuits 80 and |30 are restored to the condition above described which exists during conversation.

If the toll operator wishes to recall the dial systems A operator, plug |5| is alternately disconnected from and reconnected to jack |4| whereby relay |33 is alternately released and reoperated. Each release and reoperation of relay |33 causes the release and reoperation of relay |34 whereby the short circuit across the lower, high resistance winding of relay |3| is alternately opened and closed to cause the alternate release and reoperation of relay ||0 of trunk circuit 80. 'I'he alternate release and reoperation connect signal. causes the reoperation of relay 81.

of relay ||0 causes a corresponding release and reoperation of relays and 96 in succession. The alternate release and reoperation of relay 95 alternately connects battery through resistor 94 andl ground through resistor 95 to the sleeve conductor of jack 19, thereby causing the alternate release and reoperation of relay 51 of cord circuit 50. Each release of relay 51 closes a circuit frorn ground through the back contact of relay 51, inner lower front contact of relay 59 and back contact of relay 6| to light supervisory lamp 11. The ashing of lamp 11 signals the dial systems operator and operation of key 60 effects the operation of relay 6| to again connect the dial systems operators telephone set to the cord circuit 50. When the toll operator removes plug |5| from jack |4| to release the connection, relays |33, |34, H0, 9S and 51 release in succession, and lamp 11 is lighted steadily. If at this time the calling subscriber has restored the receiver to normal, relays 52 and 54 of cord circuit 50 have been operated as above described; and, when relay 51 releases, relay 59 is released. The release of relay 59 disconnects the windings of relay 51 from the sleeve conductor of plug 12 and relays 92 and 90 of trunk circuit 80 are thereby released in succession. The release of relay 50 reconnects the winding of relay 13 to the sleeve conductor of plug 12 and causes the release of relays 1| and 14, thereby opening the talking connection between plugs 5| and 12 and reconnecting the winding of relay 13 directly to the sleeveoi` plug 12. The release of relay 92 causes the release of relays Si?, 81 and |08; and, with both of relays 81 and released, the locking circuit of relay 84 is openedv and relay 84 releases. The release of relay 84 causes the release of relay |09 and reconnects the winding of relay 89 to the sleeve conductor of jack 19 in place of the windings of relay 92, whereby relays 89 and 13 are reoperated in series. With relays 59 and 6| released the operation of relay 13 lights lamp 11 as a dis- The reoperation of relay 89 When the dial systems A operator notices the lighting of lamp 11, plugs 5| and 12 are disconnected from jacks and 19, thereby causing the release o1 relays 13, 89 and 81 to completely restore trunk Acircuits 80 and |30 to normal and causing the release of relay 21 of trunk circuit 30. The release of relay 21 causes the release of relays 28 and 2| in succession; and with relays 8 and |5 also released, relay i8 releases. The release of relay I8 disconnects holding ground potential from the sleeve conductor; whereupon the selector and line finder switches are restored to normal in usual and well-known manner and trunk circuits I2 and 22 are completely restored to normal. v

In case the other of the two aforementioned operating methods is used by the dial systems A operator on calls which are routed to a toll operator, the plug 5| of a cord circuit 50 is connected to jack 35 in place of plug 4| of cord 40 as soon as the call information has been obtained from the calling subscriber; and plug 12 is connected to the jack 19 of an idle outgoing recording-completing trunk circuit 80. In this case the talking key is not operated, relay 5| remains normal, the toll operator obtains the call information directly from the calling subscriber, and the dial systems A operator takes no further action until the supervisoryy lamp 11 lights as a disconnect signal or flashes as a re- 11 call signal. 35, relay 53 is operated in series with relay` il; the operation of relay ZI causes the` successive operation of relays 2.8. and 2|; and the operation of relay 53. causes the operation of relay 59. The succeeding operations occur .in the manner and order hereinbefore described.

If the dial systems A operator should. connect the. plug of' a cord 4t to jack i9 in error, battery is connected through the sleeve Conductor of plug 12` and jack 1S to operate'relay 89. The.v

operation of relay 89 closes the circuit for operating relay 8T and relay S1 connects interruptor INIl to the sleeve conductor of. jack 'i9 in parallel with the Winding of relay 89. Each time the in.. terrupter ground connection is closed, the cord supervisory lamp d5 is lighted thereby indicating to the4 dial systems A operator that the wrong cord has been connected to jack; 19.,

What.y isl claimed is:

i. In a telephone system comprising a firstv visory signals from saidV subscriber recordingcompleting trunk to; said operator recordingcompleting trunk'.

In a. telephone; system comprisingr a iirst operator position and al two-Wire: subscriber recording-completing trunk' terminating at said position, a toll. operator position, a two-Wire operator recording-completing trunk extending from said firsti operator position to said. toll operator position, a recording-completing cord` circuit: at. said' irstv operator position for extending connections fromy said subscriber recordingcompleting trun.; over' said operator recordingcompleting trunk to i saidv tollv operator position; each end. of; said cord circuit comprising talking conductors. andA an sleeve conductor, means com.. prising the sleeve conductors of said recordingcompleting:cordl circuit: for repeating supervisoryv from saidrst operator position at said toll op eratorv position, a recording-completing. cordcircuit at said first operator position for extend.- ingY connections from said subscriber recording-A completing trunk over said operator recording-1 completing' trunk to. said toll operator position,l

each end of' said: cord circuit comprising talkingconductcrs anda sleeve conductor, means comprising the sleeve conductors or said recording,...

completing cord circuit for repeatingsupervisoryl/heniiilugl 5l is connected to jackv signalsv trom.` said subscriber recoming-complet-v4 inggtrunk to said operator recording-ccmpletingI trunk,` means at said toll position for applying coin collector coin return electricall potential to a talking conductor of said operator recordingcompleting trunk, and means including means individually associated with said operator record'- ingf-completing trunk for extending the coin control potential from said talking conductor through. a talking conductor of said cord. circuit to the corresponding conductor of said subscriber recording-completing trunk.

L In a telephone system, a dial systems 0perator: position, a subscriber recording-completing-trunkl for extending calls ironi calling subscribers in a local dial oilicevto said position, a' toll operator position, an operator recordingcompleting trunk extending from said dial systems operator position to said toll position, a

' vrecording-completing cord circuit at' said dial' systems operatorI position, a jack' ende-d outgoing trunk circuitv associated with the dial, systems operator end of" said operator Vrecord'ng-completing trunk', a jack ended incoming trunk circuit associated with thev toll' operator end of. said' operator recording-completing trunk, a calling signal at said toll operator position associated' with said incoming trunk circuit, means compris'- ing thev sleeve conductors of'l the. calling plug of said' cord circuit and said outgoing trunk circuit and relay means' in. said outgoing and incoming, trunk circuits for energizing said calling. signal'` upon connection of said calling plug to said'outat said toll operator position for connectionvJ-ith. said incoming trunkv circuit. to answer. a call, means in said recording-completing. cord, circuitI responsive to. the connection. of thecalling plug with said outgoing trunk circuit for connecting.r the talking. conductors. of, the, answering` plug,y to the talking conductors of the calling. plug, a. firstsupervi'sory relay in said recording-completA ing cord circuit4 for operationthrough the sleeve conductor of the. answering plug, upon connection to said4 subscriber recording-completing. trunk,l a, second supervisory relay insaid recording-completing cord. circuit, for operation. through the sleeve conductor of the calling. plug. upon: connection, to said operator recording-completing trunk,` means, comprising said first supervisory relay for transmitting supervisory signals received. over. the sleeve conductor of said' answer.-l ing. plug` through the sleeve conductor. of said.`

- calling plug, said outgoing` trunk` circuit, said operatorI recording-completing trunk. and said: incoming trunk circuit to said-.toll operator cord circuit,i andmeansfor operating said supervisory sig-nal.v in said recording-completing cord circuit responsive 'to-supervisory signals received. by said.` second supervisoryv relay4 through said outgoing; trunk. circuit, saidoperator recording-completing trunk. and. said incoming. trunk circuity from said; toll operator position.

RUSSELL B. BUCHANAN.

' References Cited in the le of this patentl UNITED STATES PATENTS Number Name Date.

2,283,789- Crocker I July 7,. 1,942 2,385,720, Molnar Sept. 25, 1945` 2,428,549 Burgener Oct. 7, 1947 2,558,571

Lamberty .Juner26, 1951i.

going trunk circuit, a supervisory signal in said.. recording-completing cord circuit, a cordcirouit- 

